The present invention relates to a turbomolecular pump which enables exhaust of a gas by interaction between rotary blades and stationary blades and/or a threaded rotor rotating at a high speed and a stator.
A general structure of a conventional turbomolecular pump is illustrated in FIG. 6. The conventional turbomolecular pump comprises a rotor R including a main shaft 10 and a rotary cylinder 12 fixed to the main shaft for rotating integrally therewith, a stator S including a fixed cylinder 14 surrounding the shaft 10, and a cylindrical casing 16 surrounding the rotary cylinder 12, which are assembled on a base B. A conductance adjusting valve 100 and a gate valve 110 are provided in the space between the turbomolecular pump and an apparatus A to be evacuated provided on the upstream side of the turbomolecular pump.
In the conventional turbomolecular pump as described above, however, driving mechanisms 101 and 111 for the individual valve units 100 and 110 are provided adjacent to the turbomolecular pump and in the proximity of the valves. This has posed a problem of scaling-up of the valve units and results in a larger overall structure of the turbomolecular pump including these valves. It is conceivable, on the other hand, to form the valve unit integrally with the turbomolecular pump, but this may lead to contamination of the apparatus to be evacuated by particles arising from the valve driving mechanism.